This book establishes a reference source for DEA that accomplishes the following seven objectives: Motivates DEA as a new approach to organizing and analyzing data beyond its origin in efficiency analyses; Presents an integrated framework, and standardized notation for understanding basic DEA models and their extension; Develops a deeper understanding of computational issues involved in solving various DEA formulations; Provides insights into the DEA process, its usage and interpretations; Highlights the range of potential uses of DEA through examples of novel applications; Provides an updated comprehensive bibliography; Facilitates the diffusion of DEA by making Chapters 1--4 and 21 available for inclusion in operations research, econometric and statistic textbooks under normal provisions which maintain original copyright status.